The invention relates to a process for retorting the hydrocarbonaceous organic matter in crushed mined solids using recycled hot heat carrying solids. More particularly, this process relates to a novel method for feeding a mixture of heat carriers and pyrolyzed mineral matter to an elutriating system.
Many processes have been suggested for retorting the carbonaceous organic matter in oil shale, coal and tar sands. Some of these processes involve heating solids and using these solids as heat carriers. The hot heat carriers and crushed mined hydrocarbonaceous mineral matter are mixed in a primary pyrolysis zone. The heat in the hot heat carriers provides much of the retoring energy. Eventually, the heat carriers are separated from the pyrolyzed mineral residue and the heat carriers are recycled through the process.
It is desirable that most of the spent mineral matter, especially fine materials like ash and dust be removed from the recycled heat carriers. This is frequently accomplished by gas elutriation. For example, in U.S. Pat. Nos. 3,803,022 and 3,844,929, the retorting stage uses special pellets as heat carriers and these carriers are separated in a primary separation stage followed by a secondary gas elutriation stage. In U.S. Pat. No. 3,164,541, the retort uses heated balls. The mineral fines and ash are separated by hot combustion gases flowing through a bed of balls in a ball heater. In U.S. Pat. No. 3,691,056, a mixture of heat carriers and pyrolyzed oil shale is fed to a fluidized bed combustion zone. When the residual organic matter is burned, the oil shale solids split and are elutriated by the combustion gas.
In all of these prior processes, a mixture of heat carrying solids and spent mineral matter is fed into some sort of chamber through which gas is flowed and the gas carrys fine mineral matter out of the chamber above the point where the mixture is fed. For purposes of this disclosure, this gas is called an elutriating gas.
When a multiple layer mixture of heat carriers and fine spent mineral matter is passed through a conveying system, for example, a gravity fed chute, the finer matter tends to form in one multiple layer stratum while the heat carriers tend to form in another stratum. When the mixture is fed into an elutriating chamber, this tends to cause surging, poor separating efficiency, and sometimes carry over of heat carriers with the fine mineral matter.